In order to address the problem of quantification of macroplastics fragmentation to microplastics in the marine environment, a simple and easily reproducible test procedure was developed for polymer films based on weathering with sunlight and application of mild mechanical stress to pinpoint the onset of fragmentation.
For polymer films, like supermarket plastic bags, it is the cumulative luminance exposure that appears to be the main indicator of the degree of weathering and it can be linked to the onset of fragmentation. A simple procedure to apply reliably and repeatedly mild mechanical stress to weathered strips has been proposed.
It is very important to have estimates of fragmentation rates of the plastics present in the marine environment if we wish to develop reliable models forecasting the environmental status of our oceans and seas.
Comparing the results from sunlight exposure on beach sand or in seawater near the surface, it is seen that fragmentation onshore is much faster. Hence, over a short period, beached plastic debris can be turned into microplastics and with the first event of high waves or strong winds, the generated microplastics are returned to the seawater where they are much more difficult to collect. Therefore, local authorities, NGOs and interested parties in general, should make every effort to regularly collect plastic debris from the beaches (especially at known debris accumulation areas) before they turn into microplastics and are returned to the sea.
AUTHOR CONTRIBUTIONS
KK helped in the analysis of the data and wrote the first draft of the manuscript, GK designed and conducted the experiments and the instrumental analysis and helped in the analysis of the data; ET conducted the experiments and the instrumental analysis and helped in the preparation of the manuscript; AG supervised the experimental measurements for the characterization of the polymer films; PP developed the image processing code in MATLAB and supervised the image analysis; FF critically reviewed the design of the whole project; NK supervised the whole project, helped in the data analysis and contributed in the write up of the manuscript.
ACKNOWLEDGMENTS
Funding by the European Union FP-7 project BIOCLEAN (grant agreement No. 312100) is highly appreciated.
SUPPLEMENTARY MATERIAL
The Supplementary Material for this article can be found online at: http://journal.frontiersin.org/article/10.3389/fmars.
2017.00084/full#supplementary-material
REFERENCES
Abdelhafidi, A., Babaghayou, I. M., Chabira, S. F., and Sebaa, M. (2015).
Impact of solar radiation effects on the physicochemical properties of polyethylene (PE) plastic film. Procedia-Social Behav. Sci.195, 2922–2929.
doi: 10.1016/j.sbspro.2015.09.002
Accinelli, C., Saccà, M. L., Mencarelli, M., and Vicari, A. (2012). Deterioration of bioplastic carrier bags in the environment and assessment of a new recycling alternative.Chemosphere89, 136–143. doi: 10.1016/j.chemosphere.2012.05.028 Andrady, A. L. (1990). “Environmental degradation of plastics under land and marine exposure conditions,” inSecond International Conference on Marine Debris (April 1989)(Honolulu, HI), 848–869.
Andrady, A. L. (2011). Microplastics in the marine environment.Mar. Pollut. Bull.
62, 1596–1605. doi: 10.1016/j.marpolbul.2011.05.030
Andrady, A. L., Pegram, J. E., and Tropsha, Y. (1993). Changes in carbonyl index and average molecular weight on embrittlement of enhanced-photodegradable polyethylenes.J. Environ. Polym. Degrad.1, 171–179. doi: 10.1007/BF01458025 Artham, T., Sudhakar, M., Venkatesan, R., Madhavan Nair, C., Murty, K.
V. G. K., and Doble, M. (2009). Biofouling and stability of synthetic polymers in sea water. Int. Biodeterior. Biodegradation 63, 884–890.
doi: 10.1016/j.ibiod.2009.03.003
Arthur, C., Baker, J., and Bamford, H. (2009).Proceedings of the International Research Workshop on the Occurrence, Effects, and Fate of Microplastic Marine Debris. Silver Spring, MD.
Barnes, D. K. A., Galgani, F., Thompson, R. C., and Barlaz, M. (2009).
Accumulation and fragmentation of plastic debris in global environments.Phil.
Trans. R. Soc.364, 1985–1998. doi: 10.1098/rstb.2008.0205
Brandon, J., Goldstein, M., and Ohman, M. D. (2016). Long-term aging and degradation of microplastic particles: comparing in situ oceanic and experimental weathering patterns. Mar. Pollut. Bull. 110, 299–308.
doi: 10.1016/j.marpolbul.2016.06.048
Brower, R. (2016). The social costs of beach litter along european coasts.Ocean Coast. Manage.138, 38–49. doi: 10.1016/j.ocecoaman.2017.01.011
Carrasco, F., Pagès, P., Pascual, S., and Colom, X. (2001). Artificial aging of high- density polyethylene by ultraviolet irradiation.Eur. Polym. J.37, 1457–1464.
doi: 10.1016/S0014-3057(00)00251-2
Cheshire, A., Adler, E., Barbière, J., and Cohen, Y. (2009). UNEP/IOC Guidelines on Survey and Monitoring of Marine Litter. UNEP Regional Seas Reports and Studies, No. 186; IOC Technical Series. Available online at: http://www.unep.org/regionalseas/marinelitter/publications/docs/Marine_
Litter_Survey_and_Monitoring_Guidelines.pdf
Cole, M., Lindeque, P., Halsband, C., and Galloway, T. S. (2011). Microplastics as contaminants in the marine environment: a review.Mar. Pollut. Bull.62, 2588–2597. doi: 10.1016/j.marpolbul.2011.09.025
da Costa, J. P., Santos, P. S., Duarte, A. C., and Rocha-Santos, T. (2016).
(Nano)plastics in the environment - Sources, fates and effects.Sci. Tot. Environ.
566–567, 15–26. doi: 10.1016/j.scitotenv.2016.05.041
Depledge, M. H., Galgani, F., Panti, C., Caliani, I., Casini, S., and Fossi, M. C. (2013). Plastic litter in the sea. Mar. Environ. Res. 92, 279–281.
doi: 10.1016/j.marenvres.2013.10.002
Directive of the European Parliament and of the Council (2013).
Directive of the European Parliament and of the Council Amending Directive 94/62/EC on Packaging and Packaging Waste to Reduce the Consumption of Lightweight Plastic Carrier Bag. Available online at:
http://eur-lex.europa.eu/legal-content/EN/ALL/?uri=CELEX:52013SC0444 Gregory, M. R. (2009). Environmental implications of plastic debris in marine
settings–entanglement, ingestion, smothering, hangers-on, hitch-hiking and alien invasions. Philos. Trans. R. Soc. Lond. B Biol. Sci. 364, 2013–2025.
doi: 10.1098/rstb.2008.0265
Hidalgo-Ruz, V., and Thiel, M. (2013). Distribution and abundance of small plastic debris on beaches in the SE Pacific (Chile): a study supported by a citizen science project. Mar. Environ. Res. 87–88, 12–18.
doi: 10.1016/j.marenvres.2013.02.015
Ho, K.-L. G., Pometto, A. L. III, and Hinz, P. N. (1999). Effects of temperature and relative humidity on polylactic acid plastic degradation.J. Polym. Environ.7, 83–92. doi: 10.1023/A:1021808317416
Ioakeimidis, C., Fotopoulou, K. N., Karapanagioti, H. K., Geraga, M., Zeri, C., Papathanassiou, E., et al. (2016). The degradation potential of PET bottles
in the marine environment: an ATR-FTIR based approach.Sci. Rep.6:23501.
doi: 10.1038/srep23501
Jabarin, S. A., and Lofgren, E. A. (1994). Photooxidative effects on properties and structure of high-density polyethylene.J. Appl. Polym. Sci.53, 411–423.
doi: 10.1002/app.1994.070530404
Kumar Sen, S., and Raut, S. (2015). Microbial degradation of low density polyethylene (LDPE): a review. J. Environ. Chem. Eng. 3, 462–473.
doi: 10.1016/j.jece.2015.01.003
Martinho, G., Balaia, N., and Pires, A. (2017). The Portuguese plastic carrier bag tax: the effects on consumers’ behavior. Waste Manage. 61, 3–12.
doi: 10.1016/j.wasman.2017.01.023
Müller, C., Townsend, K., and Matschullat, J. (2012). Experimental degradation of polymer shopping bags (standard and degradable plastic, and biodegradable) in the gastrointestinal fluids of sea turtles.Sci. Tot. Environ.416, 464–467.
doi: 10.1016/j.scitotenv.2011.10.069
O’Brine, T., and Thompson, R. C. (2010). Degradation of plastic carrier bags in the marine environment. Mar. Pollut. Bull. 60, 2279–2283.
doi: 10.1016/j.marpolbul.2010.08.005
Pham, C. K., Ramirez-Llodra, E., Alt, C. H., Amaro, T., Bergmann, M., Canals, M., et al. (2014). Marine litter distribution and density in European seas, from the shelves to deep basins.PLoS ONE9:e95839. doi: 10.1371/journal.pone.
0095839
PlasticsEurope (2015).Plastics - the Facts 2014/2015: An Analysis of European Plastics Production, Demand and Waste Data.Brussels: PlasticsEurope.
Restrepo-Flórez, J. M., Bassi, A., and Thompson, M. R. (2014). Microbial degradation and deterioration of polyethylene - a review. Int. Biodeter.
Biodegradation88, 83–90. doi: 10.1016/j.ibiod.2013.12.014
Ryan, P. G., Moore, C. J., van Franeker, J. A., and Moloney, C. L. (2009).
Monitoring the abundance of plastic debris in the marine environment.Philos.
Trans. R. Soc. Lond. B Biol. Sci.364, 1999–2012. doi: 10.1098/rstb.2008.0207 Shah, A. A., Hasan, F., Hameed, A., and Ahmed, S. (2008). Biological
degradation of plastics: a comprehensive review.Biotechnol. Adv.26, 246–265.
doi: 10.1016/j.biotechadv.2007.12.005
Stark, N. M., and Matuana, L. M. (2004). Surface chemistry changes of weathered HDPE/wood-flour composites studied by XPS and FTIR spectroscopy.Polym.
Degrad. Stabil.86, 1–9. doi: 10.1016/j.polymdegradstab.2003.11.002
Tanaka, K., Takada, H., Yamashita, R., Mizukawa, K., Fukuwaka, M. A., and Watanuki, Y. (2013). Accumulation of plastic-derived chemicals in tissues of seabirds ingesting marine plastics.Mar. Pollut. Bull.69, 219–222.
doi: 10.1016/j.marpolbul.2012.12.010
Teuten, E. L., Saquing, J. M., Knappe, D. R., Barlaz, M. A., Jonsson, S., Björn, A., et al. (2009). Transport and release of chemicals from plastics to the environment and to wildlife.Philos. Trans. R. Soc. Lond. B Biol. Sci.364, 2027–2045. doi: 10.1098/rstb.2008.0284
Tidjani, A. (2000). Comparison of formation of oxidation products during photo-oxidation of linear low density polyethylene under different natural and accelerated weathering conditions.Polym. Degrad. Stabil.68, 465–469.
doi: 10.1016/S0141-3910(00)00039-2
United Nations Environment Programme (UNEP) (2014).Plastic Debris in the Ocean. UNEP Year Book 2014 Emerging Issues Update(Nairobi), 48–53.
United Nations Environment Programme (UNEP) (2015).Plastic in Cosmetics [Fact Sheet]. Nairobi. 1.24, 1–3.
Watson, R., Revenga, C., and Kura, Y. (2006). Fishing gear associated with global marine catches. I. Database development. Fish. Res. 79, 97–102.
doi: 10.1016/j.fishres.2006.01.010
Conflict of Interest Statement: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
Copyright © 2017 Kalogerakis, Karkanorachaki, Kalogerakis, Triantafyllidi, Gotsis, Partsinevelos and Fava. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
doi: 10.3389/fmars.2017.00030
Edited by:
Francois Galgani, French Research Institute for Exploitation of the Sea (Ifremer), France
Reviewed by:
Stefano Aliani, National Research Council, Italy Olivia Gerigny, French Research Institute for Exploitation of the Sea (Ifremer), France
*Correspondence:
Britta D. Hardesty [email protected]
Specialty section:
This article was submitted to Marine Pollution, a section of the journal Frontiers in Marine Science
Received:01 November 2016 Accepted:25 January 2017 Published:31 March 2017
Citation:
Hardesty BD, Harari J, Isobe A, Lebreton L, Maximenko N, Potemra J, van Sebille E, Vethaak AD and Wilcox C (2017) Using Numerical Model Simulations to Improve the Understanding of Micro-plastic Distribution and Pathways in the Marine Environment.
Front. Mar. Sci. 4:30.
doi: 10.3389/fmars.2017.00030
Using Numerical Model Simulations to Improve the Understanding of Micro-plastic Distribution and
Pathways in the Marine Environment
Britta D. Hardesty1*, Joseph Harari2, Atsuhiko Isobe3, Laurent Lebreton4, 5,
Nikolai Maximenko6, Jim Potemra6, Erik van Sebille7, A. Dick Vethaak8, 9and Chris Wilcox1
1Commonwealth Scientific and Research Organization, Oceans and Atmosphere, Hobart, TAS, Australia,2Department of Physical, Chemical and Geological Oceanography, Oceanographic Institute, São Paulo University, São Paulo, Brazil,3Centre for Oceanic and Atmospheric Research, Research Institute for Applied Mechanics, Kyushu University, Fukuoka, Japan,4The Modelling House Ltd., Wellington, New Zealand,5The Ocean Cleanup Foundation, Delft, Netherlands,6International Pacific Research Center, School of Ocean and Earth Science and Technology, University of Hawaii, Honolulu, HI, USA,7Grantham Institute and Department of Physics, Imperial College London, London, UK,8Deltares, Marine and Coastal Systems, Delft, Netherlands,9Department of Chemistry and Biology, Institute for Environmental Studies, Vrije Universiteit Amsterdam, Amsterdam, Netherlands
Numerical modeling is one of the key tools with which we can gain insight into the distribution of marine litter, especially micro-plastics. Over the past decade, a series of numerical simulations have been constructed that specifically target floating marine litter, based on ocean models of various complexity. Some of these models include the effects of currents, waves, and wind as well as a series of processes that impact how particles interact with ocean currents, including fragmentation and degradation. Here, we give an overview of these models, including their spatial and temporal resolution, limitations, availability, and what we have learned from them. Then we focus on floating marine micro-plastics (<5 mm diameter) and we make recommendations for experimental research efforts that can improve the skill of the models by increasing our understanding of the processes that govern the dispersion of marine litter. In addition, we highlight the importance of knowing accurately the sources or entry points of marine plastic debris, including potential sources that have not been incorporated in previous studies (e.g., atmospheric contributions). Finally, we identify information gaps and priority work areas for research. We also highlight the need for appreciating and acknowledging the uncertainty that persists regarding the movement, transportation and accumulation of anthropogenic litter in the marine environment.
Keywords: accumulation modeling, fluxes, fragmentation, marine debris, microplastics, numerical modeling
INTRODUCTION
Pollution from marine plastic is a global issue of international concern. Marine litter comes from both land- and sea-based sources and can travel immense distances. Marine ecosystems worldwide are affected by human-made refuse, much of which is plastic (see Table 1 ofDerraik, 2002). Resolving the biodiversity, environmental, economic, transport, navigation, and biological invasion hazards associated with anthropogenic litter in the marine environment requires a
substantial, sustained integrated effort from individuals, industry, governments, and international governmental organizations at local to regional and global scales. The increase in global plastic production and the recent estimate of∼8 million metric tons of mismanaged plastic waste entering the ocean each year (Jambeck et al., 2015) points to the need to tackle the problem at a multitude of scales. There is no single solution, rather, a number of local and regional solutions will be required to effect change.
A necessary first step in addressing this problem is to get an estimate of the amount of plastic in the oceans, including knowledge about from where it originates, where it is accumulating, and the pathways by which it got there. This is a complex problem for a variety of reasons, including challenges in sampling bothin situ(in the water column, sediments, etc.) and at the source (e.g., riverine input, coastal input, sea-surface input, etc.). Sampling micro-plastic is particularly and challenging since it is not easily observed due to its small size, its sources include not only direct inputs but it also results from the degradation of larger plastic pieces. Furthermore, organisms can alter the pathways in the marine environment by direct transport and/or altering the density of the particles.
For these reasons, a mass budget of micro-plastic debris will be challenging to construct based on empirical data alone.
Instead, simulations using numerical models of ocean currents may be used to estimate the sources, sinks, and pathways of micro-plastic in the marine environment. This approach of integrating models predicting debris flows and distributions has been useful in extending the existing sparse observations to make estimates of budgets in some parts of the system, and flows of mass in a few cases (Cózar et al., 2014; van Sebille et al., 2015; others). Extending this approach of integrating simulation models and empirical observations can greatly improve our understanding of plastics, and particularly micro-plastics, in the marine environment at a systems level.